There are no known examples of prior-art compressors, whichever their application and operational capacity, with constructive and functional features providing the remarkable advantages of the compressor of this invention. However, by way of a simple comparative example, mention can be made of a known hydraulic compressor which transforms hydraulic energy into mechanical energy. Such compressor comprises two cylindrical bodies, aligned and connected to each other by their adjacent ends, having a sliding rod disposed therein, which has a compression head mounted on each of its opposite ends. Between each of the two heads and the corresponding opposite ends of the compressor a compressed gas chamber is defined, while a hydraulic fluid compression chamber is defined between the two heads along the adjacent portions of the cylindrical bodies. Reciprocation of the heads is caused by the injection and withdrawal of hydraulic fluid and causes the entry of gas and its subsequent discharge, after it has been compressed in the respective chambers, through respective valves located in both cylindrical bodies. Said heads comprise sealing piston rings spaced apart from each other, which define annular spaces between the cylindrical surface of each head and the matching inner surfaces of the cylindrical bodies. Said annular spaces define matching sealing chambers that prevent the passage of compressed gas into the compression hydraulic fluid chambers, wherein said sealing chambers of the heads comprise orifices communicating them with the corresponding compression hydraulic fluid chambers. Said orifices define inflow and outflow passages for pressurized hydraulic fluid, related to the forward and backward movements of the heads with respect to the gas compression chambers.
As it will be clearly explained below, the compressor of the present invention differs from the hydraulic compressor described above, in the first place, in the way it delivers displacement power to the piston, and also because of its remarkable simplicity of construction as compared to the complexity of the compressor of the prior art. While in the compressor of the prior art the source of driving power is hydraulic fluid which is working to achieve compression during the whole cycle, the operating force in the compressor of the invention is applied by means of flexible pulling strings or rigid rods fixed to a piston head, being the admission and compression chambers respectively defined on each of the sides of the piston head.
From the structural standpoint, the prior art compressor comprises two cylinders attached together, and a central wall therebetween which exerts reaction forces making the hydraulic fluid displace the piston, whereby the effective piston stroke is approximately half the total length of the cylinder. In the compressor of the invention, the effective piston stroke is practically equal to the total length of the cylinder; therefore, for the same cylinder length and diameter, the attainable compression ratio in the compressor of the invention is practically twice as much the ratio in the prior art compressor.
Additionally, it should be noted that the hydraulic compressor of the prior art will always requires a fluid compression pump, while the compressor of the invention, because of its versatility, will only need an external power source to run in high power systems, while in low power systems it can be operated manually with little effort. Contrary to the compressor of the prior art, the compressor of the invention was developed to obtain high yields of compression power with small pulling efforts exerted on a piston head by means of pulling elements fixed thereto. Since pulling efforts are easily achieved from the material and component geometry point of view, the weight and volume of the compressor can be reduced, which is an important advantage when the compressor must be transported in low weight, low power vehicles as is the case of bicycles. Additionally, when applying the pulling efforts to the piston head, preferably by means of flexible strings that project outside the compressor body, the strings can be oriented in many directions, Therefore, no extra space is required to operate the compressor as it should be the case when using, for example, rigid rods. The available space is fully utilized, and a high “available room/compression power” ratio is thus attained. However, as it has already been mentioned, in certain applications (for example in the industry), the use of rigid rods as traction means for the piston head may be appropriate. This is by no means a problem, since in this kind of application the available room is typically ample. Other differences and advantages will become apparent in the description of the compressor of the invention, where reference is made to the figures representing it in accordance with one of its preferred practical embodiments.